1. Technical Field
The present invention relates to an image recording method for reproducing a pastel color. In addition, the invention also relates to a recording material obtained by the image recording method and an image recording apparatus using the image recording method.
2. Related Art
Heretofore, color reproduction of a pastel color has been performed by various methods. The pastel color is not a clearly defined color, such as an elementary color, and is an intermediate color located in a region in which the luminance is high and the saturation is low.
As a method for reproducing this pastel color, for example, in writing instruments, such as a ballpoint pen, reproduction of a pastel color is performed using a liquid composition as an pastel ink obtained by mixing a white colorant, such as hollow resin particles or titanium oxide, and a color colorant (for example, see JP-A-03-157664, JP-A-03-277669, and JP-A-09-316382). In addition, in image formation by an ink jet recording method or the like, reproduction is performed by jetting color ink compositions, such as cyan (C), magenta (M), yellow (Y), and black (K), to a recording medium without using a white ink composition so as to obtain a color having a high luminance and a low saturation.
Incidentally, as one color model that conceptually explains the color space, the CIE/L*a*b* color coordinate system has been known. Among the three parameters (L*, a*, b*) of the CIE/L*a*b* color coordinate system, L* indicates the luminance (brightness) of color, and a* and b* each indicate the chromaticity showing the hue and the saturation. In this color coordinate system, L*=0 indicates black, and L*=100 indicates white. In addition, a* indicates a position between red and green, a negative a* value indicates green, and a positive a* value indicates red. Furthermore, b* indicates a position between yellow and blue, a negative b* value indicates blue, and a positive b* value indicates yellow. Since the L*a*b* color model is a three-dimensional system, the color space is represented by a three-dimensional space, and the luminance is shown on the vertical axis. However, when image formation is performed by an ink jet recording method using only color ink compositions such as cyan (C), magenta (M), yellow (Y), and black (K), since the color ink compositions must be thinly coated on a recording medium in order to decrease the saturation, there is a pastel color that cannot be reproduced, in particular, in a high luminance region in which L*≧80 holds.
In addition, in JP-A-2005-125690, an image recording method has been disclosed in which when an image formed using color ink compositions has not a desired concentration, the concentration is controlled by jetting a white ink on the image to perform concentration correction. However, an object of the invention disclosed in JP-A-2005-125690 is to remove individual difference in color caused between recording apparatuses and to perform a strict color control from a low to a high concentration portion; hence, when an image has a lower concentration than a desired concentration, a small amount of a white ink is jetted on the image in order to increase the luminance thereof, and this technique is not intended to reproduce a pastel color.